In the treatment of chronic rheumatic diseases in practice non-steroidal anti-phlogistic agents are used almost exclusively. The drug 1-(p-chloro-benzoyl)-2-methyl-5-methoxy-indolyl-3-acetic acid (Indomethacin) is the most frequently used agent, generally in a daily dosage of 75 mg. Although Indomethacin is the most widespread antiphlogistic agent now in use, its application is strongly limited by the undesired side-effects thereof which occur even after a relatively short treatment period. The following harmful side effects can be mentioned: in effective doses Indomethacin damages the mucosa of the stomach, it causes gastric ulcers and exhibits further detrimental side effects on the haematopoietic system.